Reactors for the catalytic reforming of hydrocarbons using steam have been known for a long time and in a multitude of embodiments. For large-scale plants, one type has established itself, in which a top-fired box furnace with vertically arranged reaction tubes, or rather reformer tubes, is used. Here, the reformer tubes are arranged in rows. The feedstock flows through the catalyst-packed reformer tubes from top to bottom and, in so doing, is subjected to a so-called reforming process.
The gas outlet temperatures are normally 850° C. and above. The process gas leaving the reformer tubes is collected in manifolds, inside or outside the fired zone of the furnace. There are burners positioned in the “gaps” between the rows of tubes, said burners firing vertically downwards. The fired zone of the whole reformer is also called the furnace box. On average the temperatures in the furnace box range from 1000 to 1250° C. The furnace walls are provided with a protective refractory lining for heat insulation and for protection from the high temperatures that prevail due to heating.
The furnace box, in which the firing devices are located, has a number of brick tunnels at the bottom of the box for collecting the flue gases. These are basically arranged horizontally, in parallel and at right angles to the vertical tubes. The flue gas generated flows through the furnace box from top to bottom and is drawn off through these flue gas tunnels at the bottom which have openings at the sides.
DE 1 767 980 discloses a tube furnace for carrying out reforming reactions in the presence of catalysts, with vertically arranged tube layers consisting of individual tubes suspended elastically at their upper ends and joined to submanifolds at their lower ends, as well as top downfiring burners parallel to the tube layers, said aforementioned submanifolds resting on the hearth of the furnace as a support for the tubes and each submanifold being connected to a manifold externally of the furnace via a lateral outlet, said manifold resting on a support permitting sliding displacement transversely thereof and being connected to a discharge or transfer conduit supported by an elastic suspension means. In the above, the submanifolds correspond to the manifolds in the present invention, albeit the submanifolds are arranged within the furnace on its hearth. The smoke discharge flues—corresponding to flue gas tunnels—are partly inside the furnace and partly below the furnace.
One type of reformer is described, for example, in detail in WO 2010/149361 A2. Essentially, a reformer consists of a feed system for the feedstocks destined for reforming, a reformer tube and outlet manifold system and a firing zone with the equipment required for firing. With regard to the so-called “box form” of the reformer, separate foundations are required to support the firing zone and the manifolds and reformer tubes. For this reason, the reformer cannot be transported as is, as without specific action the manifolds do not, for example, have a fixed connection to the firing zone. Furthermore, bulky transport braces would be required for the self-supporting brick flue gas tunnels within the firing zone.
Due to its size the reformer has, until now, been assembled from prefabricated components direct at its final destination. This assembly is lengthy and requires considerable amounts of personnel and tools. At some destinations it is not unusual for completion of the plant to be delayed due to a lack of competent personnel.